Application of a Direct Procedure for the Seismic Retrofit of a R/C School Building Equipped with Viscous Dampers

Several design methods aimed at sizing the viscous dampers to be inserted in building structures have been proposed in the last decades. Among others, the authors proposed a five-step procedure that guides the practical design from the choice of a target reduction in the seismic response of the structural system (with respect to the response of a structure without any additional damping devices) to the identification of the corresponding damping ratio and the mechanical characteristics of the commercially available viscous dampers. The original procedure requires, also at the preliminary design stage, the development of linear seismic time-history analyses for the dampers working velocities, necessary for the evaluation of the non-linear damping coefficient. In the present paper, the original five-step procedure is further simplified leading to a direct (i.e., fully analytical) procedure, which can be very useful in a preliminary design phase. The proposed direct procedure is then applied to design the added viscous dampers to be inserted in a real school building in order to improve its seismic capacity, and compared with the well-known MCEER procedure.